[lill]

I remember my 2 oldest kids planted apple seeds and they did grow, but never got to the stage of maturity

[Hopewell]

And the full name for the famous Bramley is Bramley Seedling, because the original was grown from a pip   

That's exactly why some of the varieties have seedling in their name. However most attempts to grow apples from pips produce unsatisfactory apples. Why have some plum trees that have sown themselves and the plums go straight to the animals - the original wasn't much better though.

[Plantoid]

grafting is done to control the height and the vigour of the tree in question so the bottom rootstock  is of a variety known to fit to the size wanted for the purpose while the top is the variety of fruit wanted so growing trees from seed can be done but you wont know how big it will get or how productive it will be. and some get big!     

 You can have fun with home grown from seed trees  in any case .. try grafting on several sicons of different varieties of the same fruit . ie ., coxes, russett , bramley greves etc etc.

 Whilst your from pip tree may well have a 20 foot height if it eaches maturity height you can keep it pruned low to say 6 foot like an umbrella and have all the grafted varieties within easy reach .

if you do it with plums you can end up with self pollenating trees and several varieties on each tree such as Pershore egg ( prolific producer ) Green guage and Victoria

 As a matter of fact  does anyone have a Russet tree that they would consider sending me a sicon from ( I'll pay the post ),  put it in some bubble wrap  and enclose the  heel end in a small poly bag of damp moss then slip in a length of sink waste pipe cut to size and sealed up athe ends with duct tape.
I think there is still time for me to graft one on one of my  greeves trees?